Secular Trends in Prevalence and Risk Factors of Obesity in Infants and Preschool Children in 9 Chinese Cities, 1986-2006

Introduction: No prevalence/trends were reported in Chinese infants and preschool children at the national level in this historical period of 1980s-2000s. The objectives of this paper were to present the 20-year trends in prevalence and risk factors of obesity in children below 7 years. Methods: Data obtained from a series of three sequential national surveys performed using the same design in the same 9 cities in 1986, 1996 and 2006. Weight and height (length <3 years) were measured using unified procedures at each period. Obesity was defined as a weight-for-height >= 120% of median of the NCHS/WHO international reference. A population-based paired matching case-control study was employed for screening risk factors. Results: In 1986, there was no substantial obesity epidemic, but the overall obesity prevalence reached 3.4% (boys 4.1% and girls 2.7%) in 2006, rising by 2.8 times between 1986 and 2006. Reversed gender difference, relatively higher prevalence in preschool age and more rapid increase in the second 10-year were three very obvious characteristics in China, e. g. prevalence of boys 9.9% and girls 4.9% in 2006 and increasing rate of boys 0.45 percentage points per year (pp/y) and girls 0.21 pp/y at 6-7 years groups, 0.17 pp/y of the second 10-year higher 1-fold than previous. Conclusions: China has been moving into the alarming epidemic of childhood obesity. Effort should be immediately made to prevent further deterioration. High birth weight, high parental BMI and several behavioral and family-related factors were identified and had important practical value for obesity intervention.